28 February 2008

So when I found an untapped data source for such an object, I thought it was worth having a poke. Half an hour of scripting later and Tower Bridge was on Twitter. It tells you when it’s opening and closing, what vessel is passing through, and which way that vessel is going. The times are determined by taking the scheduled time for the “lift” and subtracting five minutes for the opening, and adding five minutes for closing – the official site suggests that, at rush hour, lifts should take five minutes to open and close tops.

That’s it, really; it’s just a simple case of scraping some data and outputting it. It’s not a hugely frequent event, so won’t disturb you very much; if anything, it’s just a little insight into the heartbeat of the Thames.

As a note on its design: it’s very important to me that the bridge should talk in the first person. Whilst I’m just processing publicly available data on its behalf, Twitter is a public medium for individuals; I felt it only right that if I was going to make an object blog, the object should express something of a personality, even if it’s wrapped up in an inanimate object describing itself as “I”.

And, if you want proof that it works… how about this:

I’d set the server up yesterday; suddenly, this morning, it twittered into life, and we charged out of the office around the corner to the bridge, where the MV Dixie Queen was getting into position for its lift. As it went through, I took a picture. That was a very satisfying moment.

(Thanks to Tom for helping me bash a crontab and a few other server-shaped things into shape. If you’re interested in the technology, which is really not very relevant, it’s about thirty lines of Ruby that glues together a combination of: wget, Hpricot, John Nunemaker’s Twitter gem, and cron.)